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Date: Mon, 12 Jan 2009 19:15:09 +0100
From: Shakespeare <whatsin@xs4all.nl>
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Subject: Re: IS and AS
References: <gkfpg2$1187$1@biggoron.nerim.net> <496b6db5$0$195$e4fe514c@news.xs4all.nl> <gkft69$11jd$1@biggoron.nerim.net>
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O_TEXT schreef:
> Shakespeare a écrit :
>> O_TEXT schreef:
>>> I was wondering what is the difference between IS and AS, in general
>>> PL/SQL code.
>>>
>>>
>>> For instance of FUNCTION book_t, how can oracle know if keyword ending
>>> the header is IS or AS;
>>> I mean if header returns SELF and declare result variable before BEGIN,
>>> or if header returns SELF AS RESULT and declare nothing before BEGIN.
>>>
>>>
>>> CREATE OR REPLACE TYPE BODY book_t
>>> AS
>>>    CONSTRUCTOR FUNCTION book_t (id IN INTEGER,
>>>       title IN VARCHAR2,
>>>       isbn IN VARCHAR2,
>>>       pages IN INTEGER)
>>>       RETURN SELF AS RESULT
>>>    IS
>>>    BEGIN
>>>       SELF.id := id;
>>>       SELF.title := title;
>>>       SELF.isbn := isbn;
>>>       SELF.pages := pages;
>>>       IF isbn IS NULL OR SELF.ck_digit_okay
>>>       THEN
>>>          RETURN;
>>>       ELSE
>>>          RAISE_APPLICATION_ERROR(-20000, 'ISBN ' || isbn
>>>             || ' has bad check digit');
>>>       END IF;
>>>    END;
>>> ...
>> It's all a matter of parsing....
>>
>> Shakespeare
>>
>> BTW: in many cases, AS and IS are interchangeable.
> 
> Is it possible to know on which rule PLSQL is based for parsing?
> 
> 
> 
You could check out the syntax diagrams in the docs.

Shakespeare